It is generally known in the art to accommodate a plurality of cells in a single container to provide a battery block for use as a high-capacity storage battery for electronic vehicles and other purposes. Examples of such a container known in the art include an assembly of cylindrical metallic tubes welded to one another by spot welding, and an assembly of accommodation hole-containing cases which are surface-joined to one another to form a single unit (see PTL 1). Other examples known in the art include high-temperature storage batteries wherein storage cells are disposed in a predetermined arrangement with adjacent storage cells being partially and mutually joined together via outer cases (see PTLS 2 and 3).
However, since the storage cells suggested in the above-described patent literatures are joined together via outer cases at only several points, heat generated from the cells cannot be diffused and therefore a local temperature rise cannot be easily prevented.
On the other hand, in the future, the market would require higher capacities particularly for storage batteries for electronic vehicles. When secondary cells generated high heat due to increased capacity, it is difficult to allow the heat generated from the secondary cells to be sufficiently absorbed by adjacent cases, and risks that adjacent secondary cells go thermal runaway increase. Thus, there is a growing demand for battery cases for battery blocks which allow for efficient heat diffusion.